Buried intrusives and caldera structures in the Pozuelos Basin, Northern Puna: A 3D Gravity–Magnetic model

Abstract

The Pozuelos Basin, located along the eastern margin of the Puna Plateau in northwestern Argentina, contains several Middle Miocene dacitic volcanic complexes and has been hypothesized to overlie a large buried caldera. To refine the basin's subsurface architecture, we combine Euler deconvolution with 3D gravity–magnetic forward modeling using detailed ground geophysical data.Shallower Euler solutions cluster to the northeast of León Chico Hill, while a broader semicircular distribution of deeper solutions toward the northern sector of the study area is observed.The resulting 3D density–susceptibility model successfully reproduces the observed magnetic and gravity anomalies and reveals several non-exposed Tertiary intrusive bodies characterized by distinct natural remanent magnetization directions, indicating multiple magmatic pulses during the Tertiary.The semicircular geometry defined by the modeled intrusions is interpreted as reflecting emplacement along ring fractures, providing geophysical support for the existence of a buried middle Miocene caldera beneath the southern Pozuelos Basin. Modeled sedimentary thicknesses further agree with independent seismic interpretations. These results refine the magmatic evolution of the Northern Puna prior to the large ignimbrite flare-up of the Altiplano–Puna Volcanic Complex, and highlight new targets for mineral exploration associated with intrusive bodies located along the inferred caldera margin.